(a) Field of the Invention
This invention relates to a color correcting device for a light source in a color printer for printing color photographs from color films.
(b) Description of the Prior Art
Generally, in a color printer, a light projected out of a light source lamp is not used as an exposing light as it is but is corrected by light adjusting color filters so as to be adapted for printing. Usually, this correction is so made that the exposure time for each of the three original colors (primaries) may not be the same. This is to elevate the working efficiency. That is to say, in fact, this adjustment is made by determining the amounts of insertion of the respective color filters of Y, M and C into the exposure light path so that the exposures for the three original colors of blue, green and red may end simultaneously by using a standard color negative film (which is a negative film in which the numerical values of the respective color elements occupied in a photographed picture are most standard) (generally, making this adjustment is called "taking dead heat").
However, this adjustment must be re-made each time due to the alteration of the type of the negative film to be used and the enlarging magnification, replacement of the light source lamp to be used, the deterioration of the light source lamp in use and the dirtying or deterioration of the color filters in use.
A method wherein the amounts of insertion of the respective color filters corresponding to the variations of the type of the negative film and the enlarging magnification into the light path are memorized in advance and the respective color filters are inserted to the memorized corresponding positions each time of the variation of the negative film type or of the enlarging magnification is already adopted as an advanced method of remaking such adjustment. However, in such method, the dirtying or deterioration of the color filters and the variation of the color temperature of the lamp due to the replacement or deterioration of the lamp or to the delicate variation of the voltage can never be disposed and such factors must be re-adjusted after all.